I have the Flagstaff equivalent (25BRDS).
It's 166" from the rear wall of the trailer to the aft/rear edge of the door. Keep in mind that the rear bumper sticks out about 7 inches past the rear wall, and the spare tire is about 17" past the rear wall. So if the rear tire is the furthest point back, the door opening begins at about 183" forward of that.
I hope that helps and wasn't confusing.